The person calling isn’t as cute or innocent as this kid. This is a fraudulent outfit making bogus calls trying to sell credit card interest rate reduction services. When you call the number back, it is disconnected.
Remember, no one will ever call you out of the blue to discuss your personal finances. No legitimate business will not give you their full name address and call back number.
Hang up on these people.
Or for the more stubborn, spend as much time on the phone with them, to prevent them from reaching others who might be harmed.
Telling them you are on the National Do Not Call DNC list does no good. These people call from outside of the US over Internet circuits, are breaking the law anyway, and you would never do business with a stranger who calls out of the blue like this.
Unfortunately these people prey on easy victims, including poor, elderly, under educated or uninformed citizens in our society.